Improper initialization in Linux kernel - CVE-2026-90211
Published: September 19, 2026
Vulnerability identifier: #VU151269
CSH Severity: Low
CVSS v4: 0 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-90211
CWE-ID: CWE-665
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a local user to cause BPF programs to retain stale register values after faulting atomic operations.
The vulnerability exists due to improper initialization in bpf_jit_probe_atomic_pre() in the s390 BPF JIT compiler when processing faulting BPF_PROBE_ATOMIC read-modify-write operations. A local user can execute a BPF program containing a faulting arena atomic operation to cause BPF programs to retain stale register values after faulting atomic operations.
Only read-modify-write atomic operations carrying BPF_FETCH and BPF_CMPXCHG read an old value into a register.
Affected software
Linux kernel
How to mitigate CVE-2026-90211
Install security update from vendor's repository.